1. Field of the Invention
The invention relates to papermaking machinery and processes, and more particularly, to drum filter media cleaning apparatus.
2. Description of Related Art
Papermaking processes generate enormous amounts of dust. That dust is typically trapped by a network of hoods and, if desired, sent for final cleaning and re-use in the papermaking process. The main filter used to separate dust and particles from the air stream for cleaning and re-use is typically a large, perforated rotating drum with a filter medium installed along its exterior surface. The drum is placed within an enclosure, and dirty air with entrained paper dust and particles is expelled along its exterior surface. The dirty air is then drawn through the filter medium, cleaning it.
This process causes residue to accumulate on the exterior of the drum; the amount and type of that residue will vary with the product being produced. As the residue builds up, it can restrict the airflow through the drum, in turn causing a reduction in airflow through the hoods that capture the dust, which then causes more general problems in the manufacturing process itself.
In order to deal with buildup on the drum filter medium, an array of suction nozzles operates on the filter medium along the exterior of the drum, drawing accumulated residue off for final cleaning and re-use. These suction nozzles may, for example, be controlled with a solenoid or solenoids and timed to operate at certain intervals. However, if too much residue builds up, the suction nozzles may not be capable of drawing it off properly.